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Summer work on the NordBalt link crowned by the cable being pulled through the Curonian Lagoon

Summer work on the NordBalt link crowned by the cable being pulled through the Curonian Lagoon

On August 22-23, one of the most difficult stages of this summer’s NordBalt cable work will be implemented: a cable more than 1.5 kilometres long will be pulled through two pipes under the Curonian Lagoon, from the Klaipėda industrial region to Alksnynė. These special pipes were already laid under the Curonian Lagoon last autumn, when horizontal drilling work was done.
“Today we observed the cable pulling operation, which is one of the most complicated. All of the works being carried out for the link, including the stages that are extremely complex from a technical point of view, are going exactly according to plan, and we are sincerely grateful to our partners and contractors for that. Both their engineers and ours prepare for each job very carefully and work with great enthusiasm – this is particularly important for the successful progress of the project," said Karolis Sankovski, Member of the Board and Director of the Strategic Infrastructure Department at Lithuanian electricity transmission system operator Litgrid.
According to Mr Sankovski, pulling the cable under the Curonian Lagoon was a technological challenge for the engineers, since the 1,600–metre section of the cable was the longest that had to be pulled this summer through the pipes which were drilled in with the help of horizontal drilling technology. The use of pipes ensures that the cable as well as the environment will be better protected and the bottom of the lagoon is not affected. By situating the cable deeper down – the pipes have been laid at a depth of 17 metres from the water’s surface – it will also be possible to develop engineering communications in the future.
Two large reels and special equipment for wrapping and pulling the cable have been delivered to the construction site on the shore of the Curonian Lagoon on the Klaipėda side. One end of the cable was attached to the steel rope that was left in the pipes – this is how it was pulled out on the shore of the Curonian Lagoon at Alksnynė.
Nearly all of the cable laying work on land has already been completed. The cable was laid in metre-deep trenches and covered with concrete slabs in order to increase its security. In areas that are more difficult to access – under roads and railways – the cable was pulled through pipes.
During four months of the calmer season in the Baltic Sea, all of the planned 250 kilometres of submarine cable were laid. Two ships are currently carrying out flushing in works at the sea for the cable protection at a depth of approximately one metre. The final 150 kilometres of the submarine link will be laid in summer of next year. Work is planned to begin in April 2015.
The electric transmission line from Klaipėda to Telšiai, which is necessary to exploit the opportunities provided by the NordBalt link, is also expected to begin operation in the beginning of October. Construction work has been completed, and the line has already been evaluated by a technical committee. The 89-kilometre overhead line, which extends through the regions of Klaipėda, Plungė and Telšiai, is the first to be erected since the restoration of Lithuania’s independence.
Alongside the Klaipėda transformer substation that is being reconstructed in the village of Kiškėnai, the high voltage direct current (HVDC) converter building is also under rapid construction. Upon completion of preparatory works, metal columns have begun to be installed and the monolithic part of the building is being equipped. The HVDC converter will be one of the link’s most important elements – it will ensure conversion of electricity from alternating current to direct current. The unique technological installation near Kiškėnai will take up nearly as much space as a football stadium, and it will be as tall as a 7-8 story building at its highest part. The same kind of installation is being erected in Sweden next to the Nybro substation, where the cable will be connected to the Swedish power system.
The NordBalt link consists of two direct current power cables and a fibre optic cable for controlling the link. This link with Sweden will ensure electricity exchange between Lithuania and the Nordic countries and will become an alternative source of export and import. With a capacity of 700 MW, the NordBalt link will begin to transmit electricity at the end of 2015. Preliminary calculations set the value of the power link at LTL 1.9 billion; Lithuania and Sweden are financing 34 per cent of this amount each, while the remainder of the project cost is being funded by the European Union.
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